Because of the transition from analog to digital TV transmissions in the 470-862 MHz frequency band, certain portions of the spectrum are no longer used for TV transmissions, though the amount and exact frequency of unused spectrum varies from location to location. These unused portions of spectrum are referred to as TV White Space (TVWS). The FCC has opened up these TVWS frequencies for a variety of unlicensed uses. For example, the White Space in the 470-790 MHz bands may be used by secondary users for any radio communication that may not interfere with other incumbent/primary users. Thus, the use of LTE and other cellular technologies within the TVWS bands has recently been considered.
New entrants would not have access to licensed spectrum and would have to deploy LTE in shared spectrum such as TVWS or the industrial, scientific, and medical band (ISM). TVWS is broad and composed of a large numbers of channels often occupied by other technologies which make network discovery challenging. Since channels are shared with other operators and other radio access technologies (RATS), these channels are often polluted with localized interferers. The availability of the channels often changes over a short period, therefore the LTE system often has to be reconfigured. Additionally, small cells deployed in this spectrum may not be able to anchor the LTE system to a licensed spectrum, thus mobility management may be a challenge and the LTE system may support both uplink and downlink in the spectrum.